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| author | David S. Miller <davem@davemloft.net> | 2012-05-23 19:56:06 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-05-24 13:04:24 -0700 |
| commit | 35c9646062eba15351c6d64ea0c02176e5cb66ac (patch) | |
| tree | 46b29964dfbf21e6757b5ab629c6f748897d34e5 | |
| parent | 4efcac3a244de86593a82ca4ed945e839eb4c5af (diff) | |
| download | lwn-35c9646062eba15351c6d64ea0c02176e5cb66ac.tar.gz lwn-35c9646062eba15351c6d64ea0c02176e5cb66ac.zip | |
sparc: Increase portability of strncpy_from_user() implementation.
Hide details of maximum user address calculation in a new
asm/uaccess.h interface named user_addr_max().
Provide little-endian implementation in find_zero(), which should work
but can probably be improved.
Abstrace alignment check behind IS_UNALIGNED() macro.
Kill double-semicolon, noticed by David Howells.
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | arch/sparc/include/asm/uaccess.h | 3 | ||||
| -rw-r--r-- | arch/sparc/lib/usercopy.c | 32 |
2 files changed, 30 insertions, 5 deletions
diff --git a/arch/sparc/include/asm/uaccess.h b/arch/sparc/include/asm/uaccess.h index 42a28cfd941f..20c2acb06332 100644 --- a/arch/sparc/include/asm/uaccess.h +++ b/arch/sparc/include/asm/uaccess.h @@ -6,6 +6,9 @@ #include <asm/uaccess_32.h> #endif +#define user_addr_max() \ + (segment_eq(get_fs(), USER_DS) ? STACK_TOP : ~0UL) + extern long strncpy_from_user(char *dest, const char __user *src, long count); #endif diff --git a/arch/sparc/lib/usercopy.c b/arch/sparc/lib/usercopy.c index 87f96453403a..f61ed820cb61 100644 --- a/arch/sparc/lib/usercopy.c +++ b/arch/sparc/lib/usercopy.c @@ -3,6 +3,8 @@ #include <linux/errno.h> #include <linux/bug.h> +#include <asm/byteorder.h> + void copy_from_user_overflow(void) { WARN(1, "Buffer overflow detected!\n"); @@ -14,6 +16,8 @@ EXPORT_SYMBOL(copy_from_user_overflow); static inline long find_zero(unsigned long mask) { long byte = 0; + +#ifdef __BIG_ENDIAN #ifdef CONFIG_64BIT if (mask >> 32) mask >>= 32; @@ -25,8 +29,28 @@ static inline long find_zero(unsigned long mask) else byte += 2; return (mask >> 8) ? byte : byte + 1; +#else +#ifdef CONFIG_64BIT + if (!((unsigned int) mask)) { + mask >>= 32; + byte = 4; + } +#endif + if (!(mask & 0xffff)) { + mask >>= 16; + byte += 2; + } + return (mask & 0xff) ? byte : byte + 1; +#endif } +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS +#define IS_UNALIGNED(src, dst) 0 +#else +#define IS_UNALIGNED(src, dst) \ + (((long) dst | (long) src) & (sizeof(long) - 1)) +#endif + /* * Do a strncpy, return length of string without final '\0'. * 'count' is the user-supplied count (return 'count' if we @@ -46,7 +70,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long if (max > count) max = count; - if (((long) dst | (long) src) & (sizeof(long) - 1)) + if (IS_UNALIGNED(src, dst)) goto byte_at_a_time; while (max >= sizeof(unsigned long)) { @@ -59,7 +83,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long v = (c + high_bits) & ~rhs; *(unsigned long *)(dst+res) = c; if (v) { - v = (c & low_bits) + low_bits;; + v = (c & low_bits) + low_bits; v = ~(v | rhs); return res + find_zero(v); } @@ -119,9 +143,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count) if (unlikely(count <= 0)) return 0; - max_addr = ~0UL; - if (likely(segment_eq(get_fs(), USER_DS))) - max_addr = STACK_TOP; + max_addr = user_addr_max(); src_addr = (unsigned long)src; if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; |